NAD+ (nicotinamide adenine dinucleotide) is a coenzyme that plays a critical role in many physiologically essential processes (Ziegkel, M. Eur. J. Biochem. 267, 1550-1564, 2000). NAD is necessary for several signaling pathways including among others poly ADP-ribosylation in DNA repair, mono-ADP-ribosylation in both the immune system and G-protein-coupled signaling, and NAD is also required by sirtuins for their deacetylase activity (Garten, A. et al Trends in Endocrinology and Metabolism, 20, 130-138, 2008).
NAMPT (also known as pre-B-cell-colony-enhancing factor (PBEF) and visfatin) is an enzyme that catalyzes the phosphoribosylation of nicotinamide and is the rate-limiting enzyme in one of two pathways that salvage NAD.

Increasing evidence suggests that NAMPT inhibitors have potential as anticancer agents. Cancer cells have a higher basal turnover of NAD and also display higher energy requirements compared with normal cells. Additionally, increased NAMPT expression has been reported in colorectal cancer (Van Beijnum, J. R. et al Int. J. Cancer 101, 118-127, 2002) and NAMPT is involved in angiogenesis (Kim, S. R. et al. Biochem. Biophys. Res. Commun. 357, 150-156, 2007). Small-molecule inhibitors of NAMPT have been shown to cause depletion of intracellular NAD+ levels and ultimately induce tumor cell death (Hansen, C M et al. Anticancer Res. 20, 42111-4220, 2000) as well as inhibit tumor growth in xenograft models (Olese, U. H. et al. Mol Cancer Ther. 9, 1609-1617, 2010).
NAMPT inhibitors also have potential as therapeutic agents in inflammatory and metabolic disorders (Galli, M. et al Cancer Res. 70, 8-11, 2010). For example, NAMPT is the predominant enzyme in T and B lymphocytes. Selective inhibition of NAMPT leads to NAD+ depletion in lymphocytes blocking the expansion that accompanies autoimmune disease progression whereas cell types expressing the other NAD+ generating pathways might be spared. A small molecule NAMPT inhibitor (FK866) has been shown to selectively block proliferation and induce apoptosis of activated T cells and was efficacious in animal models of arthritis (collagen induced arthritis) (Busso, N. et al. Plos One 3, e2267, 2008). FK866 ameliorated the manifestations of experimental autoimmune encephalomyelitis (EAE), a model of T-cell mediated autoimmune disorders. (Bruzzone, Set al. Plos One 4, e7897, 2009). NaMPT activity increases NF-kB transcriptional activity in human vascular endothelial cell, resulting in MMP-2 and MMP-9 activation, suggesting a role for NAMPT inhibitors in the prevention of inflammatory mediated complications of obesity and type 2 diabetes (Adya, R. et. Al. Diabetes Care, 31, 758-760, 2008).